Electric gaseous discharge device



J, LECORGUILLIER ELECTRIC GASEOUS DISCHARGE DEVICE Filed Jan. 4, 1937 r R E m] ML IU .nl D 6 R Patented Oct. 31, 1939 PATENT oFFica ELECTRIC GASEOUS DISCHARGE DEVICE Jean Lecorguillier, Suresnes, Franceyassignor to,

UNITED STATES Socit Anonyme pour les Applications de lElectricit et des Gaz Rares, Etablissements Claude-Paz & Silva, Paris, France, a corporation of France Application January 4, 1937, Serial Ne. 118,986 p In Great Britain May 5, 1936 4 Claims. (01. 250-275) 7 It is knownto employ dischargetubes as relays without inertia by inserting a grid between the anode and'the cathode.

Such hot cathode or mercury cathode devices,

in which thefilling is mercury vapour, are known by the name of arc relays.

Hot cathode arc relays possess the disadvantage of necessitatinga certain time for rendering them operative. In fact, the principal current can only am he established whenthecathode is at the necessary temperaturewhich always takes a certain time and necessitates the use of auxiliary temporary relays. Moreover, in practice, it is not always possible to permit this delay which, for

3,315 high power units, may attain three quarters of an hour for example;

These hot cathode devices are in addition diflicult to use incases where direct current is employed. In fact, without exception, the heating of mo the cathode necessitates a source of very low tendo employ them on vehicles, railways, boats, motor lorries and the like on account'of the movement of the mass of mercury which they contain.

Finally, the mercury vapour devices of these two types have the common drawback that their operas ation depends considerably upon the temperature ofthe surroundings, the'said temperature causing a variation of the pressure of the vapour and affecting the constancy of the characteristics.

Attempts have been made, in hot cathode arc Mo relays, to replace the mercury vapour by rare gases, but in such arc relays a limitis set on the one hand by the maximum voltage between the anodes, which is much lower with gases such as argon, neon or helium than with mercury vapour,

a and on the other hand by the adsorption'of the gases by the electrodes, the effect of which is to shorten the working life. i

The present invention relates to an are relay device which enables the above-mentioned disado vantages to be obviated. This device employs a gaseous filling of krypton or xenon or a mixture of these two gases under a low pressure of between 0.01 and 0.5 mm. of mercury, in combination with analkaline metal cathode.

a The advantage of the employment of these two gases (principally of xenon) resides in the fact that, at the low pressure specified, these gases have properties approaching those of mercury, both from the point of view of ionisation potential and the potential drop in the positive column; and of theresistance. to the inverse voltage.

The alkaline metal cathode employed in this device will preferably be of the regeneratable type, ,such as'that described in U. S. Patent No. 2,041,595. Cathodes of this type possess the ad-; 10 vantage by their operating in a closed circuit, of

considerably diminishing the adsorption of the rare gases and increasingthe working life of the devices. i

for high current intensities of the order of- 25- to 40 amperes andabovathe cathode may be pro- According to a feature of the present invention,

-videcl at the corresponding current lead-in and against the tubular part forming the base of the cathode and joined to the current lead-in, with a cooling device acting by thermal conduction and. in the form of cooling ribs for example,

The effect of this device is to obviate therisk of 'crackingthe glass near the current lead-in. It

promotes thecondensation of the cathode metal,

and due to a reduction in the mass ofalkaline metal employed,n-thus enables the volume of the cathodeto be diminished. It may be advantageousto-add to the alkaline metal carborundum in the form of grains, which,

facilitates the formation of the cathode spot to the extent of enabling the discharge to be maintained with currents as low as 100 milliamperes.

The are relay according to thepresent invention may also be' provided with the following devices, l for improving its operation:

A rod-shaped resistance of agglomerated material, mineral material for example, isdisposed in the-apparatus. 'One of its ends projects into the cathode chamber and is situated at a short distance from the metallic material forming the" cathode; The other end of the rod is fixed to a current outlet.

The object of-this resistance is to reduce the igniting voltage considerably. In'faot, as soon as the cathode spot has been ignited, an ohmic drop in potential isproduced in the resistance. This drop in potential, which iscalculated to be greater than that existing in the gases, extirpates as it were the cathode discharge, and finally the end of,

the rod connected to the current outlet serves as a maintenance anode.

If the apparatus operates on a low tension supply network, 110 volts for example, it is possible in view of thesmallamountof power necessary for L mercury for example.

the maintenance, to employ a vibrator for igniting the discharge.

In the case of high tensions, it is necessary to employ an anode screen device or to dispose the anodes and their grids as far away as possible from the cathode, at the end of bent arms for example. In that case, in order to reduce the voltage of the grids, a rod of considerable resistance may be employed similar to the rod indicated in the foregoing, connected electrically to the grid by one end, the other free end terminating in the envelope body in the vicinity of the cathode.

The two figures of the accompanying drawing, which are given by way of example and without in any manner restricting the scope of the invention, will serve to make the device according to the invention better understood.

Figure 1 is diagrammatic view of a device according to the present invention, and

Fig. 2 is a fragmentary view similar to Fig. 1 showing a modification.

In Figure 1 is shown the body of the envelope l which may be of rather large volume so as to form a reserve of gas in the case of a low pressure, high tension apparatus. The filling of the envelope consists of a mixture of krypton and xenon under a very low pressure, 0.1 mm. of The envelope body I is provided with one or more arms 2, bent or straight, according to the number of phases and the voltage to be rectified or controlled. Each arm comprises an anode 4 and one or more control electrodes or grids 3. A regeneratable cathode"! of potassium for example, provided with its cooling cap 8 will be the negative pole.

At 5 is shown the resistant rod serving to reduce the igniting voltage. This resistant rod passes through the thermal barrier 9 of the cathode and terminates in the vicinity of the opening of the arms in the envelope body I. The tip of this rod, covered with a metal cap [0, is connected to a current outlet 6, the other end terminating about 10 to 15 mm. from the bath of pasty potassium constituting the cathode metal, to which has been added a considerable quantity of silicon carbide in the form of grains.

Figure 2 shows a bent arm provided with the device for lowering the voltage of the anode grids. The resistant rod is shown at H and I2, and is also bent in order to follow the contours of the bend of the arm. This rod is of high resistance so as not to increase excessively the power taken from the grid circuit. A total resistance of the order of 1 to 2 megohms is suitable in many cases. The striking of the grid then takes place at about 40 or 50 volts, sometimes less.

Having now particularly described and ascertained the nature of the said invention and in what manner the same is to be performed, I claim:

1. In an arc relay device, an envelope containing a gaseous filling at a low pressure of 0.01 to 0.5 mm. of mercury and comprising at least one of the gases krypton and xenon, said envelope being divided into communicating cathode and discharge chambers, an alkali metal cathode in the cathode chamberthe portion of the cathode chamber between the discharge chamber and the cathode constituting a condensing chamber and being constructed of a size sufficiently large relative to the cathode so that the walls thereof will be at a temperature sufficiently low for the particles of the volatilized cathode to be condensed in the cathode chamber and sufficiently high for the material condensed to fall in a molten state on the body of the cathode, means for maintaining a zone intermediate the discharge and cathode chambers at a temperature higher than that of the discharge chamber, a solid bafile between the cathode and the discharge chamber capable of preventing any particles of metal projected in a straight line from any point of the cathode from penetrating into the discharge member, at least one anode in the discharge chamber, and at least one grid interposed in said discharge chamber between each anode and said cathode.

2. In an arc relay device, an envelope containing a gaseous filling comprising at least one of the gases krypton and xenon at a low pressure of 0.01 to 0.5 mm. of mercury, said envelope being divided into communicating cathode and discharge chambers, the cathode chamber having a tubular base part, an alkali metal cathode in the tubular base part of the cathode chamber the portion of the cathode chamber between the discharge chamber and the cathode constituting a condensing chamber and being constructed of a size sufficiently large relative to the cathode so that the Walls thereof will be at a temperature sufficiently low for the particles of the volatilized cathode to be condensed in the cathode chamber and sufiiciently high for the material condensed to fall in molten state on the body of the cathode, means for maintaining a zone intermediate the discharge and cathode chambers at a temperature higher than that of the discharge chamber, and a solid baflle between the cathode and the discharge chamber capable of preventing any particles of metal projected in a straight line from any point of the cathode from penetrating into the discharge chamber, a current lead-in sealed to the base part of said discharge chamber.

at least one anode in the discharge member, at

least one grid interposed in said discharge chamber between each anode and said cathode, and a cooling device placed against the base part and limited to it.

3. In an arc relay device, an envelope containing a gaseous filling at a low pressure of 0.01 to 0.5 mm. of mercury and comprising at least one of the gases krypton and xenon, said envelope being divided into communicating cathode and discharge chambers, an alkali metal cathode in? the cathode chamber the portion of the cathode chamber between the discharge chamber and the cathode constituting a condensing chamber and being constructed of a size sufiiciently large relativeto the cathode so that the walls thereof will be at a temperature sufiiciently low for the particles of the volatilized cathode to be condensed in the cathode chamber and. sufliciently high for the material condensed to fall in a molten state .on the body of the cathode, means for maintaining a zone intermediate the discharge and cathode chambers at a temperature higher than that of the discharge chamber, a solid bafile between the cathode and the discharge chamber capable of preventing any particles of metal projected in a straight line from any point of the cathode from penetrating into the discharge member, at least one anode in the discharge chamber, at least one grid interposed in said discharge chamber between each anode and said cathode, a rod shaped resistance passing through said baiiie and terminating at one end near the bath of cathode metal, and a maintenance anode in the discharge chamber formed at the other end of said resistance.

4. In an arc relay device, an envelope containing a gaseous filling at a low pressure of 0.01 to 0.5 mm. of mercury and comprising at least one of the gases krypton and Xenon, said envelope being divided into communicating cathode and discharge chambers, an alkali metal cathode in the cathode chamber the portion of the cathode chamber between the discharge chamber and the cathode constituting a condensing chamber and being constructed of a size sufliciently large rela-- tive to the cathode so that the walls thereof will be at a temperature'sufliciently low for the particles of the volatilized cathode to be condensed in the cathode chamber and sufliciently high for the material condensed to fall in a molten state on the body of the cathode, means for maintaining a zone intermediate the discharge and cathode chambers at a temperature higher than that of the discharge chamber, a solid baifie between the cathode and the discharge chamber capable of preventing any particles of metal projected in a straight line from any point of the cathode from penetrating into the discharge member, at least one anode in the discharge chamber, at least one grid interposed in said discharge chamber between each anode and said cathode, and.

a resistant rod extending electrically at least from one of the grids, to the vicinity of the cathode.

JEAN LECORGUILLIER. 

